Model-Based Low-Noise Readout Integrated Circuit Design for Uncooled Microbolometers

Abstract

This paper presents a design model for uncooled microbolometers readout integrated circuits (ROIC). The relation between infrared focal-plane array (FPA) performance and ROIC design specification limits is shown distinctly. A simple way to find optimal operating conditions for a certain ROIC construction is also described. The signal and noise model of the ROIC is investigated in detail. A reasonable estimate of noise equivalent temperature differences for uncooled microbolometer detectors can be calculated with this model. A capacitor feedback transimpedance amplifier readout circuit is treated as an example. An experimental readout chip based on this model has been designed and implemented on silicon using a 0.5- <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm m}$</tex></formula> COMS technology. The temporal root mean square output noise voltage is 424 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm V}$</tex></formula> , which corresponds well with the measurement result. The result demonstrates the reliable prediction of achievable improvements for FPA by using this model.